The invention discloses an encoding method of low bit-rate LDPC (Low Density Parity Check) code, including the following steps: step 1, matrixes H and H are respectively constructed, the H matrix is a diagonal matrix, H is an array matrix with q multiplied by 1 and consists of q end-around-shift permutation matrixes Q; the permutation matrix Q consists of b multiplied by b step permutation matrixes Q having row weight and line weight of 1, at most one element of 1 on each diagonal line and the rest elements of 0; step 2, an H matrix with the size of equal to bq multiplied b(q+1) is constructed; step 3, check vector c is constructed, c is equal to (p1, 1=1, 2, ..., M), p1 represents the value of any first check bit, and M is the length of check bit; step 4, according to the check vector c=(p1), the inputted information vector c is equal to (dj), and coded code word c=(cc) is obtained. In the method of the invention, an algebraic method used by end-around-shift value of Q permutation matrix leads belief propagation iterative decoding algorithm to be more easily realized in parallel; bidiagonal matrix structural characteristic of H matrix can encode low rate LDPC code in a recursion manner, and has linear time computing complexity. The simulation performance is superior to the performance of the existing low rate error correcting code, thereby being capable of reaching a signal noise ratio of 0.4 dB and having ratio compatibility.